1. Field of the Invention
The present invention relates to apparatus for aerodynamically controlling tile operation of a high performance aircraft. More specifically, the invention relates to the provision of an aircraft having aerodynamic control panels which (1) are retractable flush against the side of the fuselage for low drag and observables, (2) are deployable symmetrically, through a range of intermediate positions for longitudinal trim and control functions; (3) are deployable unilaterally through a range of intermediate positions for lateral/directional trim and control functions, primarily in roll and yaw; and (4) will open an air gap between the control panel and the outer surface of the fuselage upon deployment of the panel.
2. Discussion of the Prior Art
It has always been a goal of aircraft designers to improve the aerodynamic control and maneuvering capability of aircraft. Improving control and maneuvering is especially important for supersonic fighter aircraft. This is because they have special requirements related to their ability to "track" or "aim" their fuselage in a particular desired direction. Associated with this is a further requirement to change "tracking" or "aiming" direction quickly which is commonly called maneuverability.
Maneuvering flight means flight at high angles of attack. In that flight regime aircraft experience a severe degradation of aerodynamic control, and the large empennages typically associated with fighter aircraft are the usual design solutions to cope with these deficiencies. It is desirable to reduce the size of the empennage to achieve benefits in terms of weight, drag and signature. Therefore, it is an objective of this invention to allow an empennage size reduction by providing control surfaces, primarily on the forward fuselage, which (1) substitute the controllability lost by downsizing the empennage; (2) provide nearly constant controllability throughout the angle of attack range; (3) operate only intermittently in response to a required control command, but lie retracted into the fuselage contour in times of disuse in order to save drag.
The following U.S. patents disclose various known methods of employing canards and other external control surfaces: U.S. Pat. No. 2,747,816 to Howard; U.S. Pat. No. 2,997,260 to Locke, Jr.; U.S. Pat. No. 3,279,723 to Wieland et al.; U.S. Pat. No. 4,161,300 to Schwaerzler; U.S. Pat. Nos. 4,354,646 and 4,381,091 to Raymer; and U.S. Pat. No. 4,848,700 to Lockhead.
Particularly pertinent to the present invention are the U.S. Pat. No. 2,924,400 to Ruget; U.S. Pat. No. 3,730,458 to Haberkorn; U.S. Pat. No. 3,883,094 to Mederer; U.S. Pat. No. 4,247,062 to Brueckner; U.S. Pat. No. 4,542,866 to Caldwell et al.; and U.S. Pat. No. 4,896,846 to Strom.
In this regard, the patent to Ruget discloses movable control surfaces which lie generally in the plane of the longitudinal axis of the aircraft and are pivoted about their forwardmost extremities between a stowed position retracted into the fuselage and their extended or deployed positions. Haberkorn and Caldwell et al disclose opposed control or trim fins which can be pivoted about a longitudinal axis into and out of nesting pockets on opposite sides of the fuselage of the aircraft. When fully deployed, the trim fins can be pivoted about a laterally extended axis. Mederer discloses a foldable canard assembly that includes a pair of canards folded together as a single canard extending vertically downward from the fuselage. The canards unfold to a position extending laterally from the bottom of the fuselage, but are unable to fold into a retracted position flush with an outer surface of the fuselage. The patent to Brueckner discloses a delta-winged aircraft in which a wing tip and integral vertical tail can be pivoted about a longitudinal axis and also about a lateral axis to adjust the angle of attack thereof. The patent to Strom discloses non-retracting canard surfaces which are rotatable about a lateral axis. It was in light of the current technology as exemplified by the patents just described that the present invention was conceived and has now been reduced to practice.